Rock (Likely Sedimentary)

Brown chalcedony (likely carnelian/iron-stained quartz)

Microcrystalline quartz, SiO₂; brown coloration from iron oxides/hydroxides

Eroded Brick or Pumice-like Scoria

Vesicular Basalt / Scoria (Anthropogenic variant: Eroded Firebrick)

Quartz (Smoky/Milky variety)

Silicon Dioxide (SiO2)

Quartz (Grain)

Silicon Dioxide (SiO2)

Chert (Nodule / Geode fragment)

Microcrystalline Quartz (SiO2)

White Chalcedony (likely Common Opal or Milky Quartz)

Silicon Dioxide (SiO2)

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-rich gneiss; exact identification requires a fresh surface and testing

Weathered sandstone or mudstone

Clastic siliciclastic sedimentary rock, probably quartz-rich sandstone; exact identification requires a fresh surface and tests

Granodiorite

Granodiorite (Intermediate intrusive igneous rock)

General river rock or weathered cobble

Mixed rock composition

Weathered quartz-rich rock, likely silicified limestone or quartzite

Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃) and iron-oxide staining

Shale with Vein Infillings

Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.

Banded gneiss (likely biotite-rich gneiss)

Gneiss; chiefly quartz, feldspar, biotite, and possibly hornblende

Weathered sandstone or iron-stained quartz-rich river cobble

Quartz-rich sandstone; predominantly SiO₂ with iron-oxide staining

Likely tumbled jasper or chert specimens

Microcrystalline quartz (SiO₂), commonly jasper/chert; exact identification is uncertain from the photograph

Chert (Quartz Variety)

Silicon Dioxide (SiO2)

Granite (likely biotite granite)

Coarse-grained granitic rock; chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende

White calcite (likely tumbled calcite or marble fragment)

Calcite, calcium carbonate (CaCO₃); if the specimen is granular and rock-like, it may be marble, a calcite-rich metamorphic rock

Weathered limestone or calcareous fossil fragment

Calcite-rich carbonate rock (CaCO₃), possibly fossiliferous limestone

Tumbled honey-colored chalcedony or quartzite

Microcrystalline quartz, SiO₂; exact identification requires testing

Polished orbicular granite (likely larvikite or orbicular diorite)

Quartz/feldspar-bearing granitoid with dark amphibole–biotite minerals; exact variety requires testing

Granite with Tourmaline

Felsic intrusive igneous rock containing schorl (tourmaline)

Pink-and-white quartz-rich rock, likely rose quartz matrix

Quartz (SiO₂), possibly intergrown with feldspar or chalcedony

Emerald in Matrix

Beryl (Be3Al2Si6O18)

Granite (River Pebble)

Phaneritic intrusive igneous rock (Felsic)

Orange calcite

Calcite (CaCO₃), likely honey/orange calcite

Quartz with impurities or Host Rock

SiO2 (Silicon Dioxide) with mixed silicates

Fossil-bearing limestone

Bioclastic limestone, likely containing bivalve or brachiopod impressions

Weathered iron-rich sandstone or lateritic rock

Ferruginous sandstone/laterite; chiefly quartz (SiO₂) with iron oxides such as hematite and goethite

Orange Quartzite (Tumbled)

Quartzite (SiO2)

Tumbled gray-green pebble, likely chert or altered volcanic rock

Cryptocrystalline quartz (chert), possibly silicified volcanic material

Eurasite (or Ferruginous Sandstone)

Ferruginous Sandstone (SiO2 with Fe2O3/FeOOH)

Grey River Pebble (Likely Quartz-rich or Limestone)

Clastic Sedimentary Rock (typically SiO2 or CaCO3 based)

Tumbled amber-colored chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

Garnet in Matrix (likely Almandine Garnet)

Almandine (Fe3Al2(SiO4)3)

Likely quartz fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz or quartz-rich rock

Red jasper (likely iron-rich chert)

Microcrystalline quartz (SiO₂) colored by hematite/goethite

Weathered granite (feldspathic, iron-stained granite)

Granite; primarily quartz, potassium feldspar, plagioclase feldspar, and minor mica/amphibole. Exact identification is uncertain from a single photograph.

Vesicular basalt (likely amygdaloidal basalt)

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar, clinopyroxene, and commonly olivine; vesicles are partly mineral-filled amygdules.

Blue-gray metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica assemblage; exact identification requires testing

Polished orbicular jasper (likely ocean jasper)

Silicified microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions

Basalt with inclusion

Basalt (Aphanitic-Porphyritic texture)